Valuing Your Notgeld

For a comprehensive and quick on-line guide to values the best place to go is EBay's coins & paper money area - or simply search for "notgeld" or "million mark" or similar:
Ebay coins & paper money
I would say that other sources are jsut too hap-hazard. You can try your local coin dealer but they make a living by offering well under market price, so you will definitely pay a price there.

Overview of valuing notes

The price of any obsolete currency is almost always determined by how many
copies are in circulation - on other words how rare the notes are and how
easy they are to buy.

When it comes to an individual note though, you have to take into account
its condition. If in very poor condition, if will fetch a price many times
lower than if it is totally pristine (called "uncirculated" or "UNC" for
short). Note that there are many notes from the 1920s in perfect condition, so don't think that a well worn note is in great quality - it simply isn't.

Unfortunately the very definition of market value itself can be perverted
in a way. For example, I believe some dealers specialising in Notgeld in
English speaking countries simply buy their notes from better-priced dealers
and sell them 50% to 200% higher. (Sometimes even 300% in the case of one
Australian dealer.) If you were to look at their price lists, you would
assume that their inflated prices are the current market prices, whereas I
always regard market price as the cheapest price you can expect to be able
to find the item regularly on sale for.

Also if the Saechsische Bank's 1 Million Mark note sells in UNC (ie pristine)
condition in Germany for US$2 and in the US for anything around US$7, then
the market value in this case depends on which country you're selling it in.

Grading the condition of a note

You must first know the exact condition of a note in order to value it. This
is something that collectors and dealers alike find very difficult and is
especially difficult for the novice. But some the basic terms I've used with
the valuing below are defined as follows:

Crisp Uncirculated, UNC or CU:

This means absolutely not the slightest sign of any handling or wear or
folding or anything. Some people use additional grades to distinguish
qualities such as perfect centering or other printing characteristics.

About Uncirculated, AU:

This means there is a slightly detectable imperfection such as a counting
fold on one corner or slightest fold in the center (nothing which breaks
the surface of the paper).

Extremely Fine, EF or XF:

Generally three light folds or one strong fold which breaks the surface.
There may be slight rounding at the corners.

Very Fine, VF:

May have several folds although the note is still crisp and has a
minimum of dirt.

Fine, F:

A circulated note with folds and creases, but no tears which extend
into the printing. This is your average in-the-wallet note.

Very Good, VG:

Tears and small holes can be present. The note is not crisp at all.
The is your lower quality in-the-wallet note. Lots of people don't
realize that a note in "very good" condition is really pretty lousy.

Good, G:

Small pieces missing, graffiti. A worn out note.

Fair:

Major tears, etc. A badly worn out note.

Poor:

A "rag".

High-Denomination Inflationary Notgeld

As a wildly inaccurate general rule, this higher the value on the note,
the more the note is worth. So the prices for Billionen Mark notes are on
average much higher than prices for Millionen Mark notes - but not always.

Unfortunately there is no set rule to apply. Even though Reichsbank Billionen
Mark notes fetch values into the hundreds and even thousand of dollars, the
Billionen Mark notes printed by the German railways can be bought in pristine
condition for anything as low as US$8.

Condition is very important: well-handled notes are often worth less than US$1.

Albert Pick's "Standard Catalog of World Paper Money" Volumes I and II are
probably the best (and possibly only) guide to prices available in English.
Here are some examples:

(And do note that these values are from the late 1990s and have probably changed a bit since then!)

The best suggestion I have is to check the price-list link at the top of this
page if your note isn't listed here. Otherwise you can browse the Pick
catalogues in either your town library or your local coin & currency dealer.

The Really Common Ones

People keep asking me about the same notes - so here's a list of the most
common ones, which won't make anyone an instant millionaire. (The values
here are just my guesses at a fair market value.) Note that you can only
expect half this if you sell to a dealer!

Why are most Notgeld notes so cheap? Well the problem is that these ones
were printed in the millions and there are so many still around that they
will take a long time to get scarce. So if you have some of these and they
look fairly well handled with wrinkles etc on them, then you'd be best to
hang on to them for interest's sake as they are not really worth anything.

Serienscheine (or "small change" notgeld)

The small colourful serienscheine are in general worth about US$1 each
if in pristine condition, though mail order dealers often sell them for
US$1.50. There are exceptions which will fetch higher prices but unless
you have the Lindman or Keller catalogues (in German) then you'll never
know. If a note looks like it has been well handled, its value will almost
certainly be under 10c.

Serienscheine are outside my sphere of interest, so this is really as much as
I can offer.